package com.zhang.topic.list;

/**
 * @title:
 * @author: zhang
 * @date: 2022/4/6 21:19
 * 将两个升序链表合并为一个新的 升序 链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
 */
public class MergeTwoList {
    public static class ListNode {
        int val;
        ListNode next;

        ListNode() {
        }

        ListNode(int val) {
            this.val = val;
        }

        ListNode(int val, ListNode next) {
            this.val = val;
            this.next = next;
        }
    }

    public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if (l1 == null) return l2;
        if (l2 == null) return l1;
        ListNode resultNode = new ListNode(0);
        ListNode p = resultNode;
        while (l1 != null && l2 != null) {
            if (l1.val<l2.val){
                p.next = l1;
                l1 = l1.next;
            }else {
                p.next = l2;
                l2 = l2.next;
            }
            p = p.next;
        }
        if (l1 !=null){
            p.next = l1;
        }
        if (l2!=null){
            p.next = l2;
        }
        return resultNode.next;
    }
}
